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////////////////////////////////////////////////////////////////////////////////
//
// Filename: 	xioddrds.v
//
// Project:	OpenArty, an entirely open SoC based upon the Arty platform
//
// Purpose:	For the DDR3 SDRAM, this handles the Xilinx specific portions
//		of the IO necessary to make this happen for differential I/O
//	pins.
//
// Creator:	Dan Gisselquist, Ph.D.
//		Gisselquist Technology, LLC
//
////////////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2015-2016, Gisselquist Technology, LLC
//
// This program is free software (firmware): you can redistribute it and/or
// modify it under the terms of  the GNU General Public License as published
// by the Free Software Foundation, either version 3 of the License, or (at
// your option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program.  (It's in the $(ROOT)/doc directory, run make with no
// target there if the PDF file isn't present.)  If not, see
// <http://www.gnu.org/licenses/> for a copy.
//
// License:	GPL, v3, as defined and found on www.gnu.org,
//		http://www.gnu.org/licenses/gpl.html
//
//
////////////////////////////////////////////////////////////////////////////////
//
//
module	xioddrds(i_clk, i_oe, i_v, o_v, io_p, io_n);
	input	i_clk, i_oe;
	input	[1:0]	i_v;
	output	[1:0]	o_v;
	inout		io_p, io_n;
 
	wire	w_internal, w_read_path;
 
	ODDR #(
		.DDR_CLK_EDGE("SAME_EDGE"),
		.INIT(1'b0),
		.SRTYPE("SYNC")
	) ODDRi(
		.Q(w_internal),
		.C(i_clk),
		.CE(1'b1),
		.D1(i_v[0]),
		.D2(i_v[1]),
		.R(1'b0),
		.S(1'b0));
 
	IDDR #(
		.DDR_CLK_EDGE("SAME_EDGE_PIPELINED"),
		.INIT_Q1(1'b0),
		.INIT_Q2(1'b0),
		.SRTYPE("SYNC")
	) IDDRi(
		.Q1(o_v[0]),
		.Q2(o_v[1]),
		.C(i_clk),
		.CE(1'b1),
		.D(w_read_path),
		.R(1'b0),
		.S(1'b0));
 
	IOBUFDS #(
		.DIFF_TERM("FALSE"),
		.IBUF_LOW_PWR("TRUE"),
		.IOSTANDARD("DIFF_SSTL135"),
		.SLEW("FAST")
	) IOBUFDSi(
		.O(w_read_path),
		.IO(io_p),.IOB(io_n),
		.I(w_internal),
		.T(i_oe));
endmodule